ATRP of (meth)acrylates initiated with a bifunctional initiator bearing trichloromethyl functional groups and structural analysis of the formed polymer

摘要

ATRP of methyl methacrylate (MMA),initiated with 1,3-bis{l-methyl-1-[(2,2,2-trichloroethoxy)carbonylamino]ethyl}benzene as a bifunctional initiator (BI) under CuCl catalysis was studied in the presence of 2,2'-bipyridine (bpy) or hexamethyltriethylenetetramine (HMTETA) ligands,in bulk or in toluene.With the bpy,the polymerization reaches only limited monomer conversions and products have broad MWDs.In contrast,polymerization in the presence of HMTETA is a well-controlled process,affords virtually quantitative conversion,giving PMMAs with narrow MWDs and predictable molecular weights within a range of more than one order of magnitude.NMR analysis of the prepared PMMA proved formation of linear polymers with im-measurable extent of chain branching or beta-scission as undesired side reactions.The prepared alpha,omega-dichloro-PMMAs were used as macroinitiators for ATRP of tert-butyl acrylate (t-BuA),giving the corresponding triblock copolymers with narrow MWDs and molecular weights controllable in a wide range.Block copolymerizations were performed in dimethyl formamide (DMF) or acetone in the presence of pentamethyldiethylenetriamine (PMDETA) as ligand and could be accelerated by addition of metallic copper.